Display device provided with touch sensor

ABSTRACT

According to one embodiment, a display device with a sensor, includes a pair of electrodes for a touch sensor, which are provided to extend to intersect, and a display panel which includes a plurality of display elements arranged in a matrix, a plurality of gate lines extending along display elements of the display elements which are arranged in a row direction, and a plurality of source lines extending along display elements of the display elements which are arranged in a column direction, wherein a common electrode for display provided in the display panel is also used as one of the electrodes for the touch sensor, the electrodes for the touch sensor are driven by the self-detection method, and an image display operation of the display panel and a drive operation of the electrodes for the touch sensor are performing in a time sharing manner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/601,555, filed Jan. 21, 2015, which is based upon and claims thebenefit of priority from Japanese Patent Applications No. 2014-017113,filed Jan. 31, 2014; and No. 2014-261969, filed Dec. 25, 2014, theentire contents of all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display deviceprovided with a sensor and a method of driving the display device.

BACKGROUND

In recent years, attention has been given to display devices in which atouch detection device referred to as a so-called touch panel isprovided on a display device such as a liquid crystal display device, ora touch panel and a display device are integrated as a single body, andthe display device is made to display various button images to enableinformation to be input without ordinary real buttons. Such displaydevices having a touch detection function do not need input devices suchas a keyboard, a mouse and a keypad, and thus tend to be broadly used asdisplay devices of computers, portable information terminals such ascell phones, etc.

As such a touch panel, a capacitive touch panel is known in which aplurality of electrodes each formed to extend in a single direction areintersected to each other. In this touch panel, the electrodes areconnected to a control circuit, and when supplied with an excitationcurrent from the control circuit, they detect an object close thereto.

As a display device provided with a touch sensor, a so-called in-celltouch panel is proposed in addition to a so-called on-cell touch panelin which a touch panel is provided on a display surface of a displaydevice. In the in-cell display device, a common electrode for display,which is originally provided in the display device, is also used as oneof a pair of electrodes for a touch sensor, and the other of the pair ofelectrodes (a touch detection electrode) is provided to intersect thecommon electrode.

Furthermore, as methods of detecting a touch position, a mutualdetection method and a self-detection method are known. In the mutualdetection method, a drive signal of alternating voltage is input to oneof electrodes, and a detection signal generated in the other electrodeby the drive signal is processed, to thereby detect a touch position. Inthe self-detection method, drive signals of alternating voltage areinput to electrodes, respectively, and signals generated in theelectrodes, respectively, are processed, to thereby detect a touchposition.

On the other hand, a technique of performing detection with a highsensitivity has been applied. In this technique, a stylus pen referredto as an active pen which generates static electricity is detected or afinger or the like which is in a floating state in which the finger orthe like does not touch a touch panel is detected. In such a manner, inorder to detect an object with a high sensitivity, the self-detectionmethod, not the mutual detection method, is more frequently applied.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various feature of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention.

FIG. 1 is a view schematically showing a structure of a display deviceprovided with a sensor, according to a first embodiment;

FIG. 2 is a cross-sectional view showing in more detail the displaydevice with the sensor, according to the first embodiment;

FIG. 3A is a view for explaining a principle of a self-detection methodin the display device with the sensor, according to the firstembodiment;

FIG. 3B is another view for explaining the principle of theself-detection method in the display device with the sensor, accordingto the first embodiment;

FIG. 4A is still another view for explaining the principle of theself-detection method in the display device with the sensor according tothe first embodiment;

FIG. 4B is a further view for explaining the principle of theself-detection method in the display device with the sensor according tothe first embodiment;

FIG. 5 is a view showing an example of a basic circuit for achieving theself-detection method in the display device with the sensor according tothe first embodiment;

FIG. 6 is a view showing an equivalent circuit in the case where aswitch of the display device with the sensor according to the firstembodiment is closed or opened.

FIG. 7 is a view for showing a variation waveform of a voltage of acapacitor and an output waveform of a comparator in the display devicewith the sensor according to the first embodiment;

FIG. 8 is a view showing a representative basic structure of a mutualdetection method of the display device with the sensor, according to thefirst embodiment;

FIG. 9A is a view schematically showing a structure of the displaydevice with the sensor, according to the first embodiment;

FIG. 9B is another view schematically showing the structure of thedisplay device with the sensor, according to the first embodiment;

FIG. 10A is a view for explaining driving methods of the self-detectionmethod and the mutual detection method in the display device with thesensor, according to the first embodiment;

FIG. 10B is a view for explaining driving methods of the self-detectionmethod and the mutual detection method in the display device with thesensor, according to the first embodiment;

FIG. 11 is a view for explaining why a detection sensitivity ofself-detection of the display device with the sensor according to thefirst embodiment is reduced;

FIG. 12 is a view for explaining a method of reducing an influence of aparasitic capacitance in the self-detection in the display device withthe sensor according to the first embodiment;

FIG. 13A is a view for explaining another method of reducing theinfluence of the parasitic capacitance in the self-detection in thedisplay device with the sensor according to the first embodiment;

FIG. 13B is a view for explaining still another method of reducing theinfluence of the parasitic capacitance in the self-detection in thedisplay device with the sensor according to the first embodiment;

FIG. 14A is a view for explaining a further method of reducing theinfluence of the parasitic capacitance in the self-detection in thedisplay device with the sensor according to the first embodiment;

FIG. 14B is a view for explaining a still further method of reducing theinfluence of the parasitic capacitance in the self-detection in thedisplay device with the sensor according to the first embodiment;

FIG. 15A is a plan view schematically showing structures of commonelectrodes and detection electrodes in a display device with a sensor,which was considered before consideration of the first embodiment;

FIG. 15B is a plan view schematically showing structures of commonelectrodes and detection electrodes in the sensor in the display devicewith the sensor according to the first embodiment;

FIG. 16 is a block diagram showing a structure of a circuit related tosignal switching in each of operation modes in the display device withthe sensor according to the first embodiment;

FIG. 17 is a timing chart showing an operation of a self-detection modeof the display device with the sensor according to the first embodiment;

FIG. 18 is a block diagram showing a structure of a circuit related tosignal switching in each of operation modes in a display device with asensor according to a modification of the first embodiment;

FIG. 19 is a block diagram showing a structure of a circuit related tosignal switching in each of operation modes in a display device with asensor according to another modification of the first embodiment;

FIG. 20 is a timing chart showing an operation of a self-detection modeof the display device with the sensor according to the above othermodification of the first embodiment;

FIG. 21A is a view schematically showing a structure of a sensor in adisplay device with the sensor according to a second embodiment;

FIG. 21B is another view schematically showing the structure of thedisplay device with the sensor according to the second embodiment;

FIG. 22 is a view showing a detailed structure of the sensor of thedisplay device with the sensor according to the second embodiment;

FIG. 23A is an enlarged view showing a detailed structure of the sensorof the display device with the sensor according to the secondembodiment; and

FIG. 23B is another enlarged view showing the detailed structure of thesensor of the display device with the sensor according to the secondembodiment.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

In general, according to one embodiment, a display device with a sensor,includes: a pair of electrodes for a touch sensor, which are provided toextend to intersect; and a display panel which includes a plurality ofdisplay elements arranged in a matrix, a plurality of gate linesextending along display elements of the display elements which arearranged in a row direction, and a plurality of source lines extendingalong display elements of the display elements which are arranged in acolumn direction, wherein a common electrode for display which isprovided in the display panel is also used as one of the electrodes forthe touch sensor, and the electrodes for the touch sensor are driven bya self-detection method, and an image display operation of the displaypanel and a driving operation of the electrodes for the touch sensor areperformed in a time sharing manner.

First Embodiment

FIG. 1 is a view schematically showing a structure of a display deviceDSP provided with a sensor, according to the first embodiment. It shouldbe noted that in the first embodiment, the display device is a liquidcrystal display device.

The display device comprises a display panel PNL and a backlight BLTwhich illuminates the display panel PNL from a rear surface sidethereof. The display panel PNL comprises a display portion includingdisplay pixels PX arranged in a matrix.

As shown in FIG. 1, the display portion comprises gate lines G (G1, G2,. . . ), source lines S (S1, S2, . . . ) and pixel switches SW, the gatelines G extending along display pixels PX arranged in a row direction,the source lines S extending along display pixels PX arranged in acolumn direction, and pixel switches PW close to intersections of thegate lines G and the source lines S.

The pixel switches SW comprise thin film transistors (TFTs). Gateelectrodes of the pixel switches SW are electrically connected toassociated gate lines G. Source electrodes of the pixel switches SW areelectrically connected to associated source lines S. Drain electrodes ofthe switches S are electrically connected to associated pixel electrodesPE.

Furthermore, as drive means for driving the display pixels PX, gatedrivers GD (left GD-L and right GD-R) and a source driver SD areprovided. The gate lines G are electrically connected to outputterminals of the gate drivers GD. The source lines S are electricallyconnected to output terminals of the source driver SD.

The gate drivers GD and the source driver SD are located in a peripheralarea (frame edge) of the display area. The gate drivers GD successivelyapplies on-voltages to the gate lines G to switch on the TFTs, as aresult of which the on-voltages are applied to the gate electrodes ofpixel switches SW, which are electrically connected to selected scanninglines GL, i.e., the above scanning lines GL. To be more specific, whenan on-voltage is applied to a gate electrode, electrical conduction iseffected between a source electrode and a drain electrode of a pixelswitch SW including the above gate electrode. On the other hand, thesource driver SD supplies output signals to the signal lines SL,respectively. To be more specific, when an output signal is supplied toa signal line SL, it is also supplied, through the pixel switch SW inwhich electrical conduction is effected between its source and drainelectrodes, to an associated pixel electrode PE.

Operations of the gate drivers GD and the source driver SD arecontrolled by a control circuit CTR provided outside the liquid crystaldisplay panel PNL. Furthermore, the control circuit CTR applies a commonvoltage Vcom to a common electrode COME which will be described later,and also controls an operation of the backlight BLT.

FIG. 2 is a cross-sectional view showing in detail a structure of thedisplay device DSP with the sensor according to the first embodiment.

The display device DSP with the sensor comprises the display panel PNL,the backlight BLT, a first optical element OD1 and a second opticalelement OD2. In an example shown in the figure, the display panel PNL isa liquid crystal display panel; however, as the display panel PNL,another flat panel such as an organic electroluminescence display panelmay be applied. Also, the display panel PNL as shown in the figure has astructure compliant with a lateral electric-field mode applied as adisplay mode, but may have a structure compliant with other displaymodes.

The display panel PNL comprises a first substrate SUB1, a secondsubstrate SUB2 and a liquid crystal layer LQ. The first substrate SUB1and the second substrate SUB2 are stacked together, with a gap providedbetween them. The liquid crystal layer LQ is held in the gap between thefirst substrate SUB1 and the second substrate SUB2.

The first substrate SUB1 is formed of a first insulating substrate 10having a light transmittance characteristic, such as a glass substrateor a resin material. On a side of the first insulating substrate 10which is located opposite to the second substrate SUB2, the firstsubstrate SUB1 comprises the source lines S, the common electrode COME,the pixel electrodes PE, a first insulating film 11, a second insulatingfilm 12, a third insulating film 13, a first alignment film AL1, etc.

The pixel electrodes PE and the common electrode COME form, along with apixel area of the liquid crystal layer located between those electrodes,display pixels, which are arranged in the display panel PNL.

The first insulating film 11 is provided on the first insulatingsubstrate 10. It should be noted that although it will not be explainedin detail, between the first insulating substrate 10 and the firstinsulating film 11, the gate lines G, gate electrodes of switchingelements, a semiconductor layer, etc., are provided. The source lines Sare formed on the first insulating film 11. Also, drain electrodes andsource electrodes of the switching elements, etc., are formed on thefirst insulating film 11. In the example shown in the figure, the sourcelines S extend parallel to the common electrode COME in a seconddirection Y.

The second insulating film 12 is provided on the source lines S and thefirst insulating film 11. The common electrode COME is formed on thesecond insulating film 12. In the example shown in the figure, thecommon electrode COME comprises a plurality of segments. The segments ofthe common electrode COME extend in the second direction Y, and spacedfrom each other in a first direction X. Such a common electrode COME isformed of a transparent conductive material such as indium tin oxide(ITO) or indium zinc oxide (IZO). It should be noted that in the exampleshown in the figure, although metal layers ML are formed on the commonelectrode COME to reduce the resistance of the common electrode COME,they may be omitted.

The third insulating film 13 is provided on the common electrode COME,the metal layers ML and the second insulating film 12. The pixelelectrodes PE are formed above the third insulating film 13. Also, eachof the pixel electrodes PE is located between associated adjacent two ofthe source lines S and opposite to the common electrode COME.Furthermore, the pixel electrodes PE include slits SL located oppositeto the common electrode COME. Such pixel electrodes PE are formed oftransparent conductive material such as ITO or IZO. The first alignmentfilm AL1 covers the pixel electrodes PE and the third insulating film13.

On the other hand, the second substrate SUB2 is formed of a secondinsulating substrate 20 having a light transmission characteristic, suchas a glass substrate or a resin substrate. On a side of the secondinsulating substrate 20 which is located opposite to the first substrateSUB1, the second substrate SUB2 comprises black matrixes BM, colorfilters CFR, CFG and CFB, an overcoat layer OC, a second alignment filmAL2, etc.

The black matrixes BM are formed on an inner surface of the secondinsulating substrate 20, and partition pixels. Color filters CFR, CFGand CFB are also formed on the inner surface of the second insulatingsubstrate 20, and partially stacked on the black matrixes BM. Forexample, the color filters CFR are red filters; the color filters CFGare green filters; and the color filters CFB are blue filters. Theovercoat layer OC covers the color filters CFR, CFG and CFB. Also, theovercoat layer OC is formed of transparent resin material. The secondalignment film AL2 covers the overcoat layer OC.

A detection electrode DETE is formed on an outer surface of the secondinsulating substrate 20. Also, the detection electrode DETE extends in adirection crossing segments of the common electrode COME. In the exampleshown in the figure, the detection electrode extends in the firstdirection X. The detection electrode DETE is formed of transparentconducive material such as ITO or IZO.

The backlight BLT is provided on a rear surface side of a display panelLPN. As the backlight BLT, various backlights can be applied, and forexample, a backlight employing a light emitting diode (LED) or acold-cathode fluorescent lamp (CCFL) as a light source can be applied. Adetailed explanation of the structure of the backlight BLT will beomitted.

The first optical element OD1 is provided between the first insulatingsubstrate 10 and the backlight BLT. The second optical element OD2 isprovided above the detection electrode DETE. Each of the first opticalelement OD1 and the second optical element OD2 includes at least apolarizing plate, and may include a retardation plate as occasiondemands.

Next, a touch sensor applied to the display device DSP with the sensoraccording to the first embodiment will be explained. As methods ofdetecting that the user's finger or a pen touches the touch panel or isclose to the touch panel, a self-detection method and a mutual detectionmethod are present. Principles of those detection methods will beexplained.

[Self-Detection Method]

FIGS. 3A, 3B, 4A and 4B are views for explaining a principle of aself-detection method of the display device DSP with the sensoraccording to the first embodiment.

FIGS. 3A and 3B show that the touch panel is not touched by the user'sfinger. FIG. 3A shows that due to switching of a control switch SWc, apower supply Vdd and the detection electrode DETE are connected to eachother, and the detection electrode DETE is not connected to a capacitorCcr. In this state, the detection electrode DETE, which has acapacitance Cx1, is charged. FIG. 3B shows that due to switching of thecontrol switch SWc, the power supply Vdd and the detection electrodeDETE are disconnected from each other, and the detection electrode DETEand the capacitor Ccr are connected to each other. In this state, thedetection electrode DETE having the capacitance Cx1 is dischargedthrough the capacitor Ccr.

FIGS. 4A and 4B show that the touch panel is touched by the finger ofthe user. FIG. 4A shows that due to switching of the control switch SWc,the power supply Vdd and the detection electrode DETE are connected toeach other, and the detection electrode DETE is not connected to thecapacitor Ccr. In this state, not only the detection electrode havingthe capacitance Cx1, but a user's finger close to the detectionelectrode DETE to thus have a capacitance Cx2 is charged. FIG. 4B showsthat due to switching of the control switch SWc, the power supply Vddand the detection electrode DETE are disconnected from each other, andalso the detection electrode DETE and the capacitor Ccr are connected toeach other. In this state, the detection electrode having thecapacitance Cx1 and the finger having the capacitance Cx2 are bothdischarged through the capacitor Ccr.

It should be noted that due to the presence of the capacitance Cx2, avoltage variation characteristic of the capacitor Ccr at the time ofdischarge as shown in FIG. 4B (in the case where the finger touches thepanel) clearly differs from that of the capacitor Ccr the time ofdischarge as shown in FIG. 3B (in the case where the finger does nottouch the panel). Therefore, in the self-detection method, based onvariation of the voltage variation characteristic of the capacitor Ccrwhich occurs in accordance with the presence or absence of thecapacitance Cx2, it is determined whether an input operation of thefinger or the like is performed or not.

FIG. 5 is a view showing an example of a basic circuit which achievesthe self-detection method in the display device DSP with the sensoraccording to the first embodiment.

The detection electrode DETE is connected to one of terminals of acapacitor Cr for voltage division and one of input terminals of thecomparator COMP. The detection electrode DETE has a self-capacitance Cx.

For example, the detection electrode DETE having the self-capacitance Cxis supplied with a self-sensing pulse (SSP) from a touch IC (TP-IC)through a self-sensing pulse terminal TSSP of the display device DSPwith the sensor. In the first embodiment, for example, on/off signals ofswitches SW2 and SW3 are self-sensing pulses (SSPs). The other inputterminal of the comparator COMP is connected to a supply terminal for acomparison voltage Vref.

In order to simplify an explanation, the detection electrode DETE willbe referred to as a capacitor Cx having a capacitance Cx.

The other terminal of the capacitor Cr is connected to a power supplyline of a voltage Vcc through a switch SW1, and also connected to one ofterminals of a capacitor Cc through a resistor Rc. The other terminal ofthe capacitor Cc is connected to a reference potential (e.g., a groundpotential).

The switch SW2 is connected to the reference potential and the aboveother terminal of the capacitor Cr, and the switch SW3 is connectedbetween the reference potential and the above one of the terminals ofthe capacitor Cr. The switches SW1, SW2 and SW3 and the comparator COMPare provided in the control circuit.

Next, an operation will be explained. The switch SW1 is closed (i.e.,made in the on state) at regular intervals to enable the capacitor Cc tobe charged. At the time of charging the capacitor Cc, the switches SW2and SW3 are opened (i.e., made in the off state). When the capacitor Cchas been charged, the switches SW1, SW2 and SW3 are all opened (to be inthe off state) to cause charge in the capacitor Cc to be held therein.

Then, the switches SW2 and SW3 are kept closed (in the on state) for agiven time period (whereas the switch SW1 is kept open (in the offstate)). As a result, the capacitors Cr and Cx are almost completelydischarged, and the capacitor Cc is partially discharged through theresistor Rc.

Subsequently, the switches SW1, SW2 and SW3 are all opened (to be in theoff state). As a result, charge in the capacitor Cc moved to thecapacitors Cr and Cx. In the comparator COMP, a voltage Vx of thecapacitor Cx is compared with a comparison voltage (or a thresholdvoltage) Vref.

FIG. 6 is a view showing an equivalent circuit in the case where theswitches SW1, SW2 and SW3 in the display device DSP with the sensoraccording to the first embodiment are closed and opened.

As shown in FIG. 6 showing the equivalent circuit, when the switchesSW1, SW2 and SW3 are all turned off, charge in the capacitor Cc moves tothe capacitors Cr and Cx, and then variation of the voltage Vx of thecapacitor Cx is repeatedly compared with the comparison voltage Vref inthe comparator COMP.

To be more specific, the following operation is repeatedly performed.

The switches SW2 and SW3 are kept on for a given time period (whereasthe switch SW1 is kept off). As a result, the capacitors Cr and Cx arealmost completely discharged, and the capacitor Cc is partiallydischarged thorough the resistor Rc. Then, the switches SW1, SW2 and SW3are all turned off. Consequently, charge in the capacitor Cc moves tothe capacitors Cr and Cx.

A relationship between the voltages Vr, Vc and Vx and the capacitors Cr,Cc and Cx is expressed by the following equations (1)-(3):

Vc=Vr+Vx   (1)

Vr:Vx=(1/Cr):(1/Cx)   (2)

Vx=(Cr/(Cr+Cx))×Vc   (3)

As described above, after the capacitor Cc is charged to the voltage Vcthrough the switch SW1, when the switches SW1 and SW2 are repeatedlyclosed and opened, the voltage Vc is gradually reduced, and the voltageVx of the capacitor Cx is also reduced. This operation, i.e., anoperation in which after the capacitor Cc is charged to the voltage Vc,the switches SW2 and SW3 are repeatedly closed and opened, iscontinuously performed until the voltage Vx is decreased to be less thanthe threshold voltage Vref.

FIG. 7 is a view showing a variation waveform of the voltage Vc of thecapacitor Cc and an output waveform of the comparator COMP in thedisplay device DSP with the sensor according to the first embodiment. Ahorizontal axis and a vertical axis of a coordinate system as shown inFIG. 7 indicate time and voltage, respectively.

When the switch SW1 is closed (to be in the on state), the capacitor Ccis charged in accordance with time constants of the capacitor Cc and theresistor Rc until the voltage Vc of the capacitor Cc reaches the voltageVcc. Thereafter, the switches SW1, SW2 and SW3 are all opened (to be inthe off state), and charge in the capacitor Cc moves to the capacitor Crand Cx. Then, the variation of the voltage Vx of the capacitor Cx iscompared with the comparison voltage Vref in the comparator COMP.

The characteristic of variation of the voltage Vc or the degree ofconversion thereof changes in accordance with the total capacitance ofthe capacitor Cr and Cx. That is, the greater the total capacitance ofthe capacitor Cr and Cx, the larger the amount of charge which movesfrom the capacitor Co to the capacitor Cr and Cx when the switches SW2and SW3 are opened (to be in the off state), and thus the greater thereduction of the voltage Vc. Also, the capacitance Cx varies with theproximity of the user's finger to the detection electrode DETE.

Therefore, as shown in FIG. 7, when the finger of the user is far fromthe detection electrode DETE, the voltage Vc slowly varies as indicatedby a characteristic VCP1, and when the finger is close to the detectionelectrode DETE, the voltage rapidly varies as indicated by acharacteristic VCP2. When the finger is close to the detection electrodeDETE, the rate of reduction of the voltage Vc is great, as compared withthat when the finger is far from the detection electrode DETE, since thecapacitance of the finger is added to the capacitor Cc.

The comparator COMP compares a voltage Vr with the threshold voltageVrer in synchronism with repetitive switching between closing andopening of the switches SW2 and SW3. Then, when the voltage Vr isgreater than the threshold voltage Vref (Vr>Vref), the comparator COMPobtains output pulses. However, the comparator COMP stops output pulseswhen the voltage Vr becomes less than the threshold voltage Vref(Vr<Vref).

The output pluses of the comparator COMP are monitored by a measurementapplication or a measurement circuit not shown. That is, after thecapacitor Cc is charged once, discharge is repeatedly carried out forshort time with the switches SW2 and SW3, and the voltage Vr isrepeatedly measured. At this time, a time period (MP1 or MP2) in whichon output of the comparator COMP is obtained may be measured, or thenumber of output pulses of the comparator COMP (the number of pulseswhich are output from charging of the capacitor Cc until the voltage Vrbecomes less than a voltage Vth (Vr<Vth)) may be measured.

When the user's finger is far from the detection electrode DETE, theabove time period is long, and when the finger is close to the detectionelectrode DETE, the time period is short. Also, when the finger is farfrom the detection electrode DETE, the above number of pulses outputfrom the comparator COMP is large, and when the finger is close to thedetection electrode DETE, the number of pulses output from thecomparator COMP is small.

Therefore, based on the number of pulses detected, it is possible todetermine how close the finger is to the flat surface of the touchpanel. Also, detection electrodes included in the detection electrodeDETE are arranged in a two-dimensional manner (matrix), and can thusdetect a two-dimensional position of the finger on the flat surface ofthe touch panel.

As described above, it is detected whether or not the finger of the userinfluences the detection electrode DETE. The time required for the abovedetection is, e.g., a few hundred of microseconds to the order of a fewmilliseconds, as described above.

[Mutual Detection Type]

FIG. 8 is a view showing a representative basic structure of a mutualdetection type of display device DSP with the sensor according to thefirst embodiment. The common electrode COME and the detection electrodeDETE are used. The common electrode COME includes a plurality of commonelectrodes Come1, Come2, Come3, . . . arranged in the manner of stripes.The common electrodes Come1, Come2, Come3, . . . are also arranged in ascanning (driving) direction (a Y direction or an X direction).

The detection electrode DETE includes a plurality of detectionelectrodes Dete1, Dete2, Dete3, . . . arranged in the manner of stripes(which are thinner than the common electrodes arranged in the manner ofstripes). The detection electrodes Dete1, Dete2, Dete3 . . . are alsoarranged in a direction (the X direction or the Y direction) crossingthe common electrodes Come1, Come2, Come3, . . . .

The common electrodes Come1, Come2, Come3, . . . arranged in the mannerof stripes in the common electrode COME and detection electrodes Dete1,Dete2, Dete3, . . . arranged in the manner of stripes in the detectionelectrode DETE are spaced from each other. Thus, basically, capacitorsCc are present between the common electrodes Come1, Come2, Come3, . . .and the detection electrodes Dete1, Dete2, Dete3, . . . .

The common electrodes Come1, Come2, Come3, . . . are scanned by drivepulses Tx at predetermined intervals. If the user's finger is close tothe detection electrode Dete2, when a drive pulse is supplied to thecommon electrode Come2, a pulse is obtained from the detection electrodeDete 2, which is lower in level than pulses obtained from the otherdetection electrodes arranged in the manner of stripes. The detectionelectrode DETE is used to monitor a fringing field from a Tx electrode.To be more specific, when a conductive object such as a finger isbrought close to the Tx electrode, it intercepts the fringing field. Ifthe fringing field is intercepted, the potential detected by thedetection electrode DETE is reduced.

In the mutual detection method, a detection-potential difference made bythe above reduction of the potential can be handled as a detection pulsefor a position DETP.

The above capacitance Cx varies in accordance with whether the finger isclose to or far from the detection electrode DETE. Thus, the level ofthe detection pulse also varies in accordance with whether the user'sfinger is close to or far from the detection electrode DETE. It istherefore possible to determine from the level of the detection pulsehow close the finger is to the flat surface of the touch panel. Needlessto say, a two-dimensional position of the finger on the flat surface ofthe touch panel can be detected based on an electrode driving timing ofthe drive pulse Tx and an output timing of the detection pulse.

FIGS. 9A and 9B are views schematically showing the structure of thedisplay device DSP with the sensor according to the first embodiment.FIG. 9A is a cross-sectional view of the display device DSP with thesensor, and FIG. 9B is a plan view showing the structure of the sensor.

As shown in FIG. 9A, the display device DSP with the sensor comprises anarray substrate AR, a counter-substrate CT and the liquid crystal layerLQ held between the array substrate AR and the counter-substrate CT.

In the following explanation, in order to simplify it, the commonelectrodes Come1, Come2, Come3, . . . arranged in the manner of stripesare referred to as common electrodes COME, and the detection electrodesDete1, Dete2, Dete3, . . . are referred to as detection electrodes DETE.

The array substrate AR comprises a TFT substrate 10 and the commonelectrode COME. The TFT substrate 10 comprises a transparent insulatingsubstrate formed of glass or the like, switching elements not shown,various lines including source lines, gate lines, etc., and a flatteninglayer which is an insulating film covering those lines. The commonelectrode COME is provided on the TFT substrate 10 and covered by aninsulating layer. The common electrodes included in the common electrodeCOME, for example, extend in the first direction, and are arranged inthe manner of stripes in the second direction crossing the firstdirection. The common electrodes COME are formed of transparentelectrode material such as indium tin oxide (ITO) or indium zinc oxide(IZO). In the first embodiment, the common electrodes COME are also usedas drive electrodes for the sensor.

The counter-substrate CT comprises a transparent insulating substrate 20such as glass, color filters CF, the detection electrode DETE and apolarizing plate PL. The color filters CF are covered by the overcoatlayer OC. The detection electrode DETE is provided on a main outersurface of the transparent insulating substrate 20 (which is locatedopposite to the color filters CF). The detection electrodes included inthe detection electrode DETE extend in a direction (second direction)crossing an extending direction (first direction) of the commonelectrodes, and are arranged in the manner of stripes in the firstdirection. The detection electrodes DETE are formed of transparentelectrode material such as ITO or IZO. The polarizing plate PL isprovided above the detection electrode DETE (on a side of thetransparent insulating substrate 20 which is located opposite to thecolor filters CF).

FIG. 9B is a view for explaining a configuration example of the commonelectrode COME and the detection electrode DETE. In the display deviceDSP with the sensor according to the first embodiment, the detectionmethod can be switched between the self-detection method and the mutualdetection method. Furthermore, in the self-detection method, the commonelectrode COME and the detection electrode DETE detect the position of atouch (or proximity) in the second direction and that in the firstdirection, respectively. Also, in the mutual detection method, a drivepulse is input to the common electrode COME, and a detection pulse isobtained from the detection electrode DETE. It should be noted that withrespect to the common electrode COME and the detection electrode DETE, adetection drive method and a method of effecting switching between theself-detection method and the mutual detection method will be describedlater.

In the display device DSP with the sensor according to the firstembodiment, sensor electrodes (the common electrode COME and thedetection electrode DETE) are featured in structure in that the commonelectrode COME has a vertical COME structure. This will be described indetail later.

FIGS. 10A and 10B are views for explaining driving methods of theself-detection method and the mutual detection method in the displaydevice DSP with the sensor according to the first embodiment. Asdescribed above, since the common electrodes COME, which are used indisplaying an image, are also used as electrodes for touch positiondetection, an image display operation and a touch position detectionoperation are performed in a time sharing manner.

In the mutual detection method as shown in FIG. 10A, a time period forprocessing is divided into time periods for displaying an image(hereinafter each referred to as an image display time period and timeperiods for detecting a touch position (hereinafter each referred to asa touch position detection time period), and in a single frame timeperiod, image display time periods and touch position detection timeperiods are alternately applied. To be more specific, an operation foroutputting image signals (SIGn) corresponding to respective colors inresponse to a signal (SELR/G/B) for selecting three colors of RGB isperformed for a plurality of divided display lines, and thereafter amutual detection operation in which drive pulses Tx are input to thecommon electrodes included in the common electrode COME is performed.That is, the plurality of divided display lines and the commonelectrodes included in the common electrode COME are successivelysubjected to the above operations.

In the self-detection method as shown in FIG. 10B, after an image of asingle frame is displayed, a self-detection operation is performed byinputting drive pulses to all the common electrodes included in thecommon electrode COME. To be more specific, an operation for outputtingimage signals (SIGn) corresponding to respective colors in response to asignal (SELR/G/B) for selecting three colors of RGB is performed withrespect to all the display lines, and thereafter the self-detectionoperation is performed by inputting drive pulses to all the commonelectrodes included in the common electrode COME.

It should be noted that in the self-detection method, a detectionoperation is not dividedly performed, i.e., it is performed in a singletime period. This is because the sensitivity of the detection operationcan be improved by obtaining data on the detection in the single timeperiod. However, since in the self-detection method, the detectionoperation can be performed with a higher sensitivity than in the mutualdetection method, it is not limited to that in the manner as shown inFIG. 10B; that is, it may be performed in a manner as shown in 10A.

FIG. 11 is a view for explaining why a detection sensitivity is reducedin the self-detection in the display device DSP with the sensoraccording to the first embodiment.

In the self-detection method as explained above, a capacitance Cx2 whichthe finger close to the electrode has influences a detectionsensitivity. It should be noted that as shown in FIG. 11, since thecommon electrode COME is provided close to the source lines S and thegate lines G, parasitic capacitances between the common electrode COMEand the source lines S and the gate lines G are very great, and greatlyvary due to a film thickness difference, temperature, etc., thus causinga great error, and thus reducing the detection sensitivity. Furthermore,due to the presence of a great parasitic capacitance, the commonelectrode COME cannot be driven with a desired waveform having a goodresponsiveness. It was therefore hard to apply the common electrode COMEto the self-detection method.

FIG. 12 is a view for explaining a method of reducing an influence of aparasitic capacitance in the self-detection in the display device DSPwith the sensor according to the first embodiment.

As shown in FIG. 12, switches for connection with the gate lines G andswitches for connection with the source lines S are provided, and duringthe touch position detection time period, the switches are opened tocause the gate lines G and the source lines S to be in a floating state.As a result, the influence of the parasitic capacitance is completelyeliminated in principle, and thus the common electrode COME can bedriven with a desired waveform.

FIGS. 13A and 13B are views for explaining another method of reducingthe influence of the parasitic capacitance in the self-detection in thedisplay device DSP with the sensor according to the first embodiment.

As shown in FIG. 13A, switches for connection with the gate lines G andswitches for connection with the source lines S are provided, and duringthe touch position detection time period, the switches for connectionwith the gate lines G are opened to cause the gate lines G to be in afloating state. Then, as shown in FIG. 13B, identical waveformssynchronizing with the detection waveform of the common electrode COMEare input to the source lines S. As a result, the influence of theparasitic capacitance is reduced to enable the common electrode COME tobe driven with a desired waveform.

It is preferable that source lines S to which the identical waveformssynchronizing with the drive waveform are input be driven by physicallyshort-circuiting the source lines S and common electrodes in the commonelectrode COME to which drive pulses having the above drive waveform areinput. Normally, resistors in the electrode COME are formed oftransparent electrodes (ITO, IZO) or the like, and have a higherresistance than that of source electrodes formed of metal. The abovedriving is performed by establishing a short-circuit, to thereby reducethe resistances of COME lines, and thus reduce the power consumption. Astructure to be applied is not limited to the above structure. That is,identical waveforms synchronizing with the drive waveform may also beinput to source lines S not associated with the above common electrodesin the common electrode COME.

FIGS. 14A and 14B are views for explaining a further method of reducingthe influence of the parasitic capacitance in the self-detection in thedisplay device DSP with the sensor according to the first embodiment.

As shown in FIG. 14A, switches for connection with the gate lines G andswitches for connection with the source lines S are provided; and theyare closed during the touch position detection time period. That is, thesource lines S and the gate lines G are not made to float. Furthermore,as shown in FIG. 14B, identical waveforms synchronizing with the drivewaveform for the common electrode COME are input to the gate lines G andthe source lines S. Thereby, the common electrode COME can be drivenwith a desired waveform. It should be noted that signals for driving thegate lines G are made to have a waveform of a potential at whichswitching transistors can be kept non-conducting (in the off state).This is intended to prevent switching transistors provided at respectivepixels from conducting (being made in the on state) to cause a leakageat the pixels and degrade a display quality due to the leakage.

It should be noted that in the case where identical waveformssynchronizing with the drive waveform are input to source lines S, theymay be input to source lines S associated with common electrodesincluded in the common electrode COME to which drive pulses having theabove drive waveform are input, or may be input to source lines S notassociated with the common electrodes to which the drive pulses havingthe drive waveform are input.

FIG. 15A is a plan view schematically showing structures of commonelectrodes and detection electrodes in a sensor in a display device DSPwith the sensor, which was considered before consideration of the firstembodiment. FIG. 15B is a plan view schematically showing structures ofthe common electrodes and the detection electrodes in the sensor in thedisplay device DSP with the sensor according to the first embodiment.

Referring to FIG. 15A, the common electrode COME and the source lines Sare provided to intersect each other. Thus, in the self-detectionmethod, lines from the common electrodes included in the commonelectrode COME extend laterally as shown in the figure, and ICs (blackscanners) are provided at frame edge portions on both sides as shown inthe figure. Thus, the frame edge portions each have a large size. On theother hand, in the display device DSP with the sensor according to thefirst embodiment, as shown in FIG. 15B, the common electrodes includedin the common electrode COME are provided to extend parallel to thesource lines S. Thus, the lines from the common electrodes included inthe common electrode COME can be extended toward an FPC side as shown inthe figure (in an extension of the source lines S). Therefore, in thefirst embodiment, ICs (block Scanners) do not need to be provided atframe edge portions on both sides as shown in the figure, and the frameedge portions are thus made smaller.

If the common electrodes for use in displaying an image are used aselectrodes for the self-detection method, it is necessary to furtherprovide lines for supplying a detection signal from the commonelectrodes. Thus, a frame edge of a liquid crystal element is greatlywidened, as a result of which the number of liquid panels to be obtainedfrom a mother sheet is decreased. In addition, this runs counter to ademand for narrower frame edges, which is made in view of a set design.

In the first embodiment, sensor lines from the common electrodesincluded in the common electrode COME are provided to extend to aswitching portion 40 provided on the FRC side of the array substrate AR(on an extension of each of the source lines S), without extendingthrough the frame edge portions. The switching portion 40 switches thesignal lines to be connected to the common electrodes included in thecommon electrode COME in accordance with an operation mode (a displaymode, a mutual detection mode or a self-detection mode) of the displayportion. Furthermore, the switching portion 40 is connected to a touchIC (TP-IC) for touch processing which is provided outward of thedetection electrode DETE, with a flexible printed circuit (FPC)interposed between the switching portion 40 and the touch IC (TP-IC).Also, the sensor lines from the detection electrodes included in thedetection electrode DETE are connected to the touch IC (TP-IC). In sucha manner, in the first embodiment, ICs (block scanners) for touch drivedo not need to be provided on both sides as shown in the figure, and theframe edge portions can be further narrowed, as compared with thestructure as shown in FIG. 15A.

Furthermore, in the first embodiment, during the touch positiondetection time period, the common electrodes included in the commonelectrode COME are electrically connected in parallel with the sourcelines S. This structure will be explained in detail later. By virtue ofthe structure, the resistances of the common electrodes included in thecommon electrode COME, which are sensor lines, can be reduced.

Then, the structure and operation of a circuit for achieving the abovesensor driving operation will be explained.

FIG. 16 is a block diagram of the structure of a circuit related toswitching between signals in each of operation modes in the displaydevice DSP with the sensor according to the first embodiment.

As described above, the common electrodes included in the commonelectrode COME extend in the second direction Y and are arranged apartfrom each other in the first direction X. To be more specific, if asingle common electrode is associated with a single block, blocksassociated with the common electrodes included in the common electrodeCOME are arranged in the first direction X. Furthermore, a plurality ofpixels are associated with each of the common electrodes included in thecommon electrode COME. That is, a group of pixels in a given singleblock are associated with a common electrode associated with the singleblock. FIG. 16 shows a common electrode associated with a block j and agroup of pixels in the block j; and a common electrode associated with ablock j+1 and a group of pixels in the block j+1.

As shown in FIG. 16, source lines S are used in supplying image signalsto pixels and thus connected to the pixels, with a source-line floatportion 31 interposed between the source lines S and the pixels. In thesource-line float portion 31, switches are provided for the source linesS as switches which effect switching between connection anddisconnection of the source lines S, and opening and closing operationsof the switches are controlled with source-line connection/disconnectionsignals SEL1 and SEL2. It should be noted that FIG. 16 shows a structureof a two-column selection method in which one source line S is connectedto two columns of pixels; however, the method to be applied is notlimited to the two-column selection method. That is, an arbitraryselection method such as a one-column selection method or a three-columnselection method can also be applied. Also, it should be noted that whena source line S is disconnected by an associated switch, it floats.

As shown in FIG. 16, gate lines G are connected to a gate-line floatportion 30. Furthermore, the gate-line float portion 30 is supplied witha gate-off signal (Gate_Off). In the gate-line float portion 30, ANDcircuits are provided for respective rows of pixels, and output signalswhich are logical products (AND) of gate signals and gate-off signals(Gate _Off) are input to pixels arranged in the first direction X. Inthe first embodiment, when the gate-off signal (Gate_Off) is made in theon state, the gate line G in the floating state.

It should be noted that FIG. 16 shows two rows of pixels and two blocksas a matter of convenience for explanation; however, actually,source-line float portions 31 and gate-line float portions 30 areprovided for all blocks and all rows of pixels.

Then, the structure of a circuit as shown in a lower portion of FIG. 16will be explained.

A common electrode corresponding to a block j is connected to one end ofeach of block-j mode changeover switches 41 j and 42 j. The other end ofthe block-j mode changeover switch 41 j is connected to the touch IC(TP-IC). The block-j mode changeover switch 41 j is closed (to be in theconnected state) by a self-mode signal (Self_EN) in a self-detectionmode. To be more specific, in the self-detection mode, a self-sensingpulse (SSP) from the touch IC (TP-IC) is supplied to the commonelectrode COME through the self-sensing pulse terminal (TSSP). As aresult, the touch IC (TP-IC) can directly control the common electrodeCOME as a self-detection sensor.

On the other hand, the block-j mode changeover switch 42 j is closed (tobe in the connected state) by a self-mode signal (Self_EN) in a mutualdetection mode or an image display mode. The other end of the block-jmode changeover switch 42 j is connected to a supply line for adirect-current drive signal (VCOMDC) through a block-j direct-currentselect switch 43 j, and also to a supply line for an alternating-currentdrive signal (TSVCOM) through a block-j alternating-current selectswitch 44 j. The block-j direct-current select switch 43 j is closed (tobe in the connected state) by a block-j selection portion 45 j in theimage display mode to supply the direct-current drive signal (VCOMDC) tothe common electrode COME. The block-j alternating-current select switch44 j is closed (to be in the connected state) in the mutual detectionmode by the block-j selection portion 45 j to supply thealternating-current drive signal (TSVCOM), i.e., drive pulses Tx, to thecommon electrode COME.

The block-j selection portion 45 j comprises a shift register and anoutput buffer, and shifts an input direct-current select signal(VCOMSEL) in synchronism with a clock (not shown) in the mutualdetection mode. The block-j alternating-current select switch 44 j iskept closed (in the connected state) until the direct-current selectsignal (VCOMSEL) is input to a block-(j+1) selection portion 45 j+1which is subsequent to the block-j selection portion 45 j. In such amanner, common electrodes included in the common electrode COME, towhich drive pulses Tx are to be input, are selected.

It should be noted that the block j+1 has the same circuit configurationas the block j, and its explanation will be omitted.

FIG. 17 is a timing chart showing an operation of the self-detectionmode of the display device DSP with the sensor according to the firstembodiment.

If the self-detection mode is selected as the touch detection mode, whenthe touch position detection time period starts at time T1, a prechargevoltage is set for an image display signal Sn. At this time, source-lineconnection/disconnection signals SEL1 and SEL2 are made in the on state,and the precharge voltage (e.g., a low-level voltage) is applied to thesource lines S. This is intended to eliminate an influence of a residualvoltage in the source lines S when the common electrode COME is vibratedby a drive pulse having a drive waveform.

At time T2, the source-line connection/disconnection signals SEL1 andSEL2 are made in the off state. Thereby, the source lines S float. Onthe other hand, at time T2, the gate-off signal (Gate_Off) is made inthe on state. As a result, the gate lines G are made in the floatingstate. Furthermore, at time T2, a self-mode signal (Self_EN) is to be inthe on state. As a result, mode changeover switches 41 for all blocksare closed (i.e., made in a conductive state) (mode changeover switches42 are opened, i.e., made in the disconnected state), and the commonelectrodes COME are connected to the touch IC (TP-IC), which is providedexternally. The touch IC (TP-IC) directly inputs self-sensing pulses(SSPs) to the common electrodes COME through self-sensing pulseterminals (TSSP) to perform a detection operation.

At time T3, the touch position detection time period ends (thedisplaying time period starts), the gate-off signal (Gate_Off) is to bein the off state, and the gate lines G stop floating. Furthermore, theself-mode signal (Self_EN) is to be in the off state, and the switchesoperate to supply the direct-current drive signal (VCOMDC) to the commonelectrodes COME. Furthermore, the source-line connection/disconnectionsignals SEL1 and SEL2 are to be in the on state to connect the sourceline S and pixels to each other and stop floating of the source line S.

FIG. 18 is a block diagram showing a structure of a circuit related tosignal switching in each of the operation modes in a modification of thedisplay device DSP with the sensor according to the first embodiment.

Unlike the circuit as shown in FIG. 16, in the circuit as shown in FIG.18, with respect to each of blocks, a self-mode signal (Self_EN) is alsoinput to a block selection portion 45. Furthermore, although a modechangeover switch 41 is provided, no mode changeover switch 42 isprovided. The block selection portion 45 causes a direct current selectswitch 43 and an alternating current select switch 44 to be opened, whenthe self-mode signal (Self_EN) is to be in the on state. On the otherhand, when the self-mode signal (Self_EN) is to be in the on state, themode changeover switch 41 is closed (to be in the conductive state), andan associated common electrode COME is connected to the touch IC(TP-IC), which is externally provided. The operation of the circuit ofthe above modification is the same as that of the circuit as shown inFIG. 16, and its explanation will be omitted. In the circuit of themodification, the number of switches to be provided can be decreased.

FIG. 19 is a block diagram showing a structure of a circuit related tosignal switching in each of operation modes in a display device DSP witha sensor, according to another modification of the first embodiment.Referring to FIG. 19, a further circuit is provided and connected inparallel with a source line S and an associated common electrode COME inthe touch position detection time period. Structural elements identicalto those in the first embodiment will be denoted by the same referencenumerals as in the first embodiment, and their detailed explanationswill be omitted. FIG. 19 shows only a circuit for a block j in orderthat an explanation be simplified, and circuits for the other blockshave the same structure as the circuit for the block j. It should benoted that the states of contact points of switches as shown in FIG. 19are those when the self-detection mode is applied.

The common electrodes COME extend in a vertical direction (the seconddirection Y), and arranged apart from each other in a lateral direction(the first direction X). To be more specific, if a single commonelectrode COME is associated with a single block, common electrodes COMEassociated with blocks are arranged in the first direction X.Furthermore, a single common electrode COME is associated with aplurality of pixels. That is, a group of pixels in a single block areassociated with the common electrode COME associated with the singleblock.

Source lines S are used in supplying an image signal to pixels andconnected to the pixels through a source-line float portion 31. In thesource-line float portion 31, switches for effecting switching betweenconnection and disconnection of the source lines S are provided for thesource lines S, and opening and closing operations of those switches arecontrolled with source-line connection/disconnection signals SEL1 andSEL2.

Furthermore, referring to FIG. 19, a direct-current drive signal(VCOMDC) is input to an upper part of the associated common electrodeCOME through a source-line connecting portion 50. In the source-lineconnecting portion 50, switches are provided to supply a direct-currentselect signal (VCOMSEL) to switch the following modes: a mode ofsupplying the direct-current drive signal (VCOMDC) to the associatedcommon electrode COME; and a mode of connecting the source line S andthe common electrode COME in parallel with each other. In the state asshown in FIG. 19, the direct-current drive signal (VCOMDC) is notsupplied to the common electrode COME, and source lines S and the commonelectrode COME are connected together.

Gate lines G are connected to the gate-line float portion 30.Furthermore, to the gate-line float portion 30, a gate-off signal(Gate_Off) is input. In the gate-line float portion 30, AND circuits areprovided for respective rows, a logical product of a gate signal and thegate-off signal (Gate_Off) is input as an output signal to pixelsarranged in the first direction X. In the other above modification ofthe first embodiment, when the gate-off signal (Gate_Off) is to be inthe on state, the gate line G floats.

Next, a structure of a circuit as shown in a lower portion of FIG. 19will be explained.

The common electrode COME which is associated with the block j isconnected to one of ends of the block-j mode changeover switch 41 j. Theother end of the block-j mode changeover switch 41 j is connected to thetouch IC (TP-IC). In the self-detection mode, the block-j modechangeover switch 41 j is closed (to be in the connected state) by theself-mode signal (Self_EN). To be more specific, in the self-detectionmode, a self-sensing pulse (SSP) from the touch IC (TP-IC) is suppliedto the above associated common electrode COME through the self-sensingpulse terminal (TSSP). Thus, the touch IC (TP-IC) can directly controlthe common electrode COME as a self-detection sensor.

Furthermore, the common electrode COME of the block j is also connectedto one-end portions of direct-current select switches 46. Switching ofthe direct-current select switches 46 is effected by the direct-currentselect signal (VCOMSEL). In the detection mode, the switching of thedirect-current select switches 46 is effected to cause the commonelectrode COME and source lines S to be connected to each other, and inthe image display mode, the switching of the direct-current selectswitches 46 is effected to cause the direct-current drive signal(VCOMDC) to be input to the common electrode COME.

Thus, in the self-detection mode, the source lines S and the commonelectrode COME of the block j are electrically connected in parallelwith each other through the source-line connecting portion 50 and thedirect-current select switches 46, and thus the self-sensing pulse (SSP)is supplied to the source lines S and the common electrode COME of theblock j at the same time. Furthermore, at this time, as shown in FIG.19, the common electrode COME of the block j is connected to groundlines (TSIG1, TSIG2 and TSIG3) through block-j ground select switches 47j.

On the other hand, in the mutual detection mode, the block-jalternating-current select switch 44 j is closed (to be in the connectedstate), and the block-j ground select switches 47 j are opened. As aresult, the alternating-current drive signal (TSVCOM), i.e., the drivepulse Tx, is supplied to the above common electrode COME.

The block-j selection portion 45 j comprises a shift resistor and anoutput buffer, and in the mutual detection mode, shifts an inputdirect-current select signal (VCOMSEL) in synchronism with a clock (notshown). Until the direct-current select signal (VCOMSEL) is input to ablock-(j+1) selecting portion at a subsequent stage, the block-jalternating-current select switches 44 j are kept closed (in theconnected state). Thereby, the common electrode COME in a block to whichthe drive pulse Tx is to be input is selected. Furthermore, in theself-detection mode, the block-j selection portion 45 j closes theblock-j ground select switches 47 j (i.e., causes it to be in theconnected state) in response to the self-mode signal (Self_EN), toconnect the source lines S to a ground line.

FIG. 20 is a timing chart showing an operation of the self-detectionmode of a display device DSP with a sensor according to anothermodification of the first embodiment.

In the case where the self-detection mode is selected as a touchdetection mode, when the touch detection time period starts at the timeT1, the source-line connection/disconnection signals SEL1 and SEL2 areto be in the on state. At this time, an image signal Sn is not output.At time T2, the source-line connection/disconnection signals SEL1 andSEL2 are kept in the on state. Thereby, the source lines S are keptconnected to the pixels.

On the other hand, at time T2, the gate-off signal (Gate_Off) is to bein the on state. As a result, the gate lines G is in the floating state.Furthermore, at time T2, direct-current select signals (VCOMSEL)supplied in upper and lower regions corresponding to upper and lowerportions of FIG. 19 are to be in the on state. As a result, switching ofthe direct-current select switches 46 is effected to connect the abovecommon electrode COME and the source lines S. That is, the commonelectrode COME and the source lines S are connected to each other in theupper and lower regions. Also, the self-mode signal (Self_EN) is to bein the on state. As a result, the above common electrode COME isconnected to the touch IC (TP-IC) provided externally, and the touch IC(TP-IC) directly inputs a self-sensing pulse (SSP) to the commonelectrode COME to perform the detection operation.

At time T3, when the touch detection time period ends (the display timeperiod starts), the gate-off signal (Gate_Off) is to be in the offstate, and the gate lines G stop floating. Further, the self-mode signal(Self_EN) is to be in the off state, and the above switching occurs suchthat a direct-current drive signal is supplied to the above commonelectrode COME. Furthermore, after to be in the off state once, thesource-line connection/disconnection signals SEL1 and SEL2 are to be inthe on state, and an image signal for display is supplied to the pixelsthrough the source lines S.

It should be noted that in the circuit as shown in FIG. 19, identicalvibration waveforms are input to the source lines S and the associatedcommon electrode COME at the same time. Thus, a desired vibrationwaveform can be input to the common electrode COME. It should be notedthat since the gate lines G float, identical vibration waveforms may beinput to the gate lines G and the common electrode COME or no vibrationwaveforms may be input.

It should be noted that switching between the self-detection mode andthe mutual detection mode can be effected, when a control unit (notshown) provided externally designates one of those detection modes as anappropriate mode with a self-mode signal (Self_EN), after for example,checking a detected state of the touch sensor. How to use this switchingbetween the self-detection mode and the mutual detection mode can bedetermined in accordance with various usage of the display device withthe sensor.

Second Embodiment

The second embodiment is different from the first embodiment instructure of the common electrode COME. Thus, structural elementsidentical or similar to those in the first element electrodes will bedenoted by the same structural elements as in the first embodiment, andtheir explanations will be omitted.

FIGS. 21A and 21B are views schematically showing a structure of adisplay device DSP with a sensor according to the second embodiment.FIG. 21A is a cross-sectional view of the display device DSP with thesensor, and FIG. 21B is a plan view showing a structure of the sensor.

As shown in FIG. 21A, the display device DSP with the sensor comprisesan array substrate AR, a counter-substrate CT, and a liquid crystallayer LQ held between the array substrate AR and the counter-substrateCT. The counter-substrate CT comprises a transparent insulatingsubstrate 20 formed of glass or the like, a color filter CF, a detectionelectrode DETE and a polarizing plate PL. The structure of thecounter-substrate CT is the same as that in the first embodiment. Thearray substrate AR comprises a TFT substrate 10 and a common electrodeCOME. With respect to the array substrate AR, the structure of thecommon electrode COME is different from that in the first embodiment asdescribed below. It should be noted that the common electrode COME alsofunctions as a sensor which detects a variation of a capacitance as inthe first embodiment.

As shown in FIG. 21B, the common electrode COME comprises a plurality ofelectrodes SX which are electrically independent of each other. Theelectrodes SX are provided on the TFT substrate 10 and arranged in amatrix along the first direction X and the second direction Y. In thesecond embodiment, each of the electrodes SX is formed of a transparentconductive material such as ITO or IZO.

In the second embodiment, each of the electrodes SX is rectangular. Oneof sides of each electrode SX has a length of 9 mm or less, preferably4-5 mm. This is intended to detect a touch of a finger with a highprecision in consideration of a size of finger which is approximately 9mm□. Furthermore, it is preferable that in both vertical and horizontaldirections, the gap between any adjacent two of the electrodes SX be 10microns or less. This is determined in consideration of space for sourcelines S, gate lines G and lead lines (not shown) for electricallyconnecting the electrodes SX and a switching portion 60.

FIG. 22 is a view showing a detailed structure of the sensor of thedisplay device DSP with the sensor according to the second embodiment.

In regions covered by the electrodes SX, a plurality of pixel electrodesPE are provided, and arranged in the row and column directions. Betweenpixel electrodes PE arranged adjacent to each other in the rowdirection, lead lines 62 are provided to extend in the column direction.Also, each of the lead lines 62 is electrically connected to arespective one of the electrodes SX by at least one contact portion 61.In such a manner, the lead lines 62 connected to the electrodes SX,respectively, are connected to a switching portion 60.

FIGS. 23A and 23B are enlarged views showing the detailed structure ofthe display device DSP with the sensor according to the secondembodiment. FIG. 23A is an enlarged plan view showing the structure ofthe sensor, and FIG. 23B is an enlarged cross-sectional view of thearray substrate AR in the display device DSP with the sensor, which istaken along a cutting-plane line XX′.

As shown in FIG. 23B, an interlayer film formed of an insulating film(an organic film PLN in the case shown in the FIG. 23B) is provided tocover the source lines S, and pixel electrodes PE formed of transparentconductive material such as ITO or IZO are provided on the interlayerfilm. Furthermore, inter-electrode insulating films formed of inorganicinsulating film PIL are provided to cover the pixel electrodes PE. Theelectrodes SX, which are formed of transparent conductive material suchas ITO or IZO, are formed on the inter-electrode insulating films PIL.On the other hand, between the adjacent pixel electrodes PE, the leadlines 62, which are formed of metallic material, are provided to extendin the column direction, and also covered by the inter-electrodeinsulating film PIL. In each of the lead lines 62, at least one contactportion 61 formed of metallic material is provided in an appropriateposition. Thus, contact portions 61 electrically connect the lead lines62 and the electrodes SX, respectively.

Next, with reference to FIGS. 16, 18 and 19, it will be explained howthe display device DSP with the sensor according to the secondembodiment is operated with the electrodes SX having the abovestructure.

[Operation According to the Self-Detection Method]

When the display device DSP with the sensor is operated in theself-detection mode, touch detection is performed by operating only theelectrodes SX in the self-detection mode without using the detectionelectrode DETE. The switching portion 60 switches the lead lines 62 tocause the electrodes SX to function as block common electrodes COME,respectively. Then, it connects the electrodes SX to block modechangeover switches 41, respectively. Thereby, the electrodes SX and thetouch IC (TP-IC) are electrically connected to each other, and thus atouch drive operation can be performed in the self-detection mode byself-sensing pulses (SSP) from the touch IC (TP-IC).

It should be noted that the self-sensing pulses (SSP) in theself-detection, as shown in FIG. 22, are supplied to the electrodes SXthrough the lead lines 62 provided between the pixel electrodes,respectively. To be more specific, the block common electrodes COME asshown in FIGS. 16, 18 and 19 correspond to the electrodes SX,respectively, and the number of block common electrodes COME whichsupply self-sensing pulses (SSP) is increased, as compared with thestructure according to the first embodiment. Inevitably, the number ofblock mode changeover switches 41 to be switched by the switchingportion 60 is also increased in accordance with increasing of the numberof the electrodes SX.

The lead lines 62 are provided between the adjacent pixels as shown inFIG. 22, and the number of regions between adjacent pixels, in whichlead lines 62 are not provided, is also increased or decreased inaccordance with the number of the electrodes SX.

It should be noted that in the operation in the self-detection mode, itis possible that self-sensing pulses (SSP) are supplied to all theelectrodes SX at the same time to perform sensing with all theelectrodes, or it is also possible that the electrodes SX are dividedinto groups, and self-sensing pulses (SSP) are supplied to the groups ina time sharing manner to perform self-sensing.

[Operation According to the Mutual Detection Method]

When the display device DSP with the sensor is operated in the mutualdetection mode, it is operated to cause the electrodes SX to function ascommon electrodes COME in the common electrode COME to which drivepulses Tx are to be input, and to obtain detection pulses Rx withdetection electrodes DETE. The switching portion 60 electricallyconnects lead lines 62 from electrodes SX arranged in the same columnsuch that the electrodes SX are connected in series to each other in thecolumn direction. Then, the lead lines 62 in each of columns areconnected to the mode changeover switches 42 in an associated one of theblocks, or the electrodes SX arranged in the same column are driven atthe same time. Thereby, an alternating-current drive signal TSVCOM canbe input to the electrodes SX arranged in the column direction (the samecolumn) to perform the touch drive operation in the mutual detectionmode.

It should be noted that in the mutual detection method, the electrodesSX are connected in series to each other in the column direction, andmade in the same manner as the block common electrodes COME in the firstembodiment. Therefore, it suffices that since the alternating-currentdrive signal TSVCOM is also input to the electrodes SX connected inseries to each other, the mode changeover switches 42, the alternatingcurrent select switch 44, the block selection portion 45 j, etc., asshown in FIGS. 16, 18 and 19 are made to have the same structures asthose in the first embodiment.

[Operation in the Display Mode]

When the display device DSP with the sensor is operated in the displaymode, the electrodes SX are given a common voltage Vcom, and caused tooperate as common electrodes COME. The switching portion 60 electricallyconnects lead lines 62 from electrodes SX arranged in the same columnsuch that the electrodes SX are connected in series to each other in thecolumn direction. Then, in each of the columns, lead lines 62 areconnected to the mode changeover switch 42 in an associated one of theblocks. Alternatively, the electrodes SX arranged in the same column aredriven at the same time. Thereby, a direct-current drive signal VCOMDCis input to the electrodes SX arranged in the same column to perform adisplay operation with a driver IC.

It should be noted that in the display mode, the electrodes SX areconnected in series to each other in the column direction, and are madein the same manner as the block common electrodes COME in the firstembodiment. Therefore, it suffices that since the direct-current drivesignal VCOMDC is input to the electrodes SX connected in series to eachother in the column direction, the mode changeover switches 42, thedirect current select switch 43, the block selection portion 45 j, etc.,as shown in FIGS. 16, 18 and 19, are made to have the same structure asthose in the first embodiment.

It should be noted that in the second embodiment, in the self-detectionmode, only the electrodes SX are used without using the detectionelectrode DETE, and thus the great distance between the finger and theelectrodes SX might cause a problem. Therefore, the detection electrodesDETE (detection electrodes Dete1, Dete2, Dete3, . . . ), which arearranged in the manner of stripes, are made thinner to improve thesensitivity of the electrodes SX. According to a research made by theinventors, the detection electrodes Dete1, Dete2, Dete3, . . . arrangedin the shape of stripes each have a width of 1-10 microns, preferably 5microns, and the distance between adjacent detection electrodes Dete1,Dete2, Dete3, . . . is 1-10 mm, preferably 5 mm. For example, thedetection electrodes Dete1, Dete2, Dete3, . . . arranged in the mannerof stripes can also be provided between the electrodes SX shown as aplan view of the display device DSP with the sensor.

It should be noted that in the self detection in the display device DSPwith the sensor according to the second embodiment, the influence of theparasitic capacitance can be reduced as in the first embodiment. Thatis, as explained above with reference to FIGS. 12-14, the influence ofthe parasitic capacitance in the self-detection time period can bereduced by performing the following operations in combination with eachother as appropriate: causing the gate lines G and the source lines S tobe in the floating state; and inputting of identical waveformssynchronizing with the drive waveform of the common electrode COME.

Furthermore, the display device DSP with the sensor according to thesecond embodiment is operated such that the electrodes SX are connectedin series to each other in the column direction to form the commonelectrode COME; however, the electrodes SX can also be connected inseries to each other in the row direction to form the common electrodeCOME. This structure in which the electrodes SX are connected in seriesto each other in the row direction corresponds to the structure of thedisplay device DSP with the sensor as shown in FIG. 15A. In this case,the detection electrodes DETE are provided to extend in the verticaldirection. In this case, it suffices that a drive circuit is formedcompliant with the structures as shown in FIGS. 16, 18 and 19. Also,with respect to the method of reducing the parasitic capacitance, itsuffices that causing the gate lines G and the source lines S to be inthe floating sate and inputting of identical waveforms synchronizingwith the drive waveform of the common electrode COME are applied incombination as appropriate. Thereby, it is possible to achieve a similaroperation to that in the second embodiment.

In the display device with the sensor according to each of the aboveembodiments, even if an in-cell type display device is adopted, theself-detection method can be applied. Furthermore, switching between theself-detection method and the mutual detection method can beappropriately effected in accordance with how to use the display device.

Those functions may be applied to a circuit on glass of the TFT, andframe edge portions can be made smaller, since space, etc. on the FPCside of a driver IC can be effectively used. If a scanner circuit isincorporated into a drive IC, it is also possible to provide a liquidcrystal element including frame edges which are substantially the sameas those in a crystal element not having a touch function. Furthermore,if it is set that a detection signal of mutual self is sent by a touchIC which detects a touch, only the number of lines to be added isincreased without the need to provide a scanner circuit, etc. This is agreat advantage.

All display devices which can be put to practical use by a person withordinary skill in the art by changing as appropriate the designs of thedisplay devices according to the above embodiments are covered by thedisclosure of the present application with respect to the presentinvention, as long as they are made to have the subject matter of thepresent invention.

It can be understood that various modifications of the embodiments ofthe present invention can be conceived by a person with ordinary skillin the art, and also fall within the scope of disclosure of the presentapplication with respect to the present invention. For example, withrespect to the above embodiments, if a person with ordinary skill in theart adds or deletes a structural element or changes a design asappropriate, or adds or omits a step or changes a design, a modificationobtained by such a change also falls within the scope of disclosure ofthe present application with respect to the present invention, as longas it has the subject matter of the present invention.

In addition, in addition to the above advantages obtained by the aboveembodiments, if another or other advantages can be obviously consideredto be obtained by the embodiment or embodiments from the specificationor can be conceived as appropriate by a person with ordinary sill in theart from the specification, it is understood that such another or otheradvantages can also be obtained by the present invention.

It is also possible to make various inventions by combining asappropriate the structural elements as disclosed with respect to theabove embodiments. For example, some of the structural elements in theembodiments may be deleted. Also, structural elements used in both theembodiments may be combined as appropriate.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A display device provided with a touch sensor,comprising: a plurality of gate lines arranged in a first direction toextend in a second direction crossing the first direction, a pluralityof signal lines arranged in the second direction to extend in the firstdirection, a plurality of display elements provided in areas districtedby the plurality of the gate lines and the plurality of signal lines, aplurality of common electrodes separated from each other, arranged in amatrix, and overlapping the plurality of gate lines and the plurality ofsignal lines in plan view, and a plurality of pixel electrodes opposedto the plurality of common electrodes, wherein a display operation and atouch detection operation are performed in a time divisional manner,wherein in a display operation period, the plurality of gate lines aresupplied with selection signals to select one or more display elementsin a row direction among the plurality of display elements, and theplurality of pixel electrodes are supplied with a plurality of displaysignals through the plurality of signal lines, wherein the plurality ofcommon electrodes are selectively supplied with an alternating voltagesignal and sense an external object by a self-detection method in atouch detection operation period, and at least the plurality of signallines of the plurality of gate lines and the plurality of signal linesare provided with a substantially same amplitude signal as thealternating voltage signal supplied to the plurality of commonelectrodes.
 2. A display device provided with a touch sensor accordingto claim 1, wherein the plurality of gate lines and the plurality ofsignal lines are not electrically connected to a touch detectioncircuit.
 3. A display device provided with a touch sensor according toclaim 1, wherein the plurality of signal lines are provided with asubstantially same amplitude signal as the alternating voltage signalsupplied to the plurality of common electrodes.
 4. A display deviceprovided with a touch sensor according to claim 1, wherein the pluralityof gate lines and the plurality of signal lines are provided with asubstantially same amplitude signal as the alternating voltage signalsupplied to the plurality of common electrodes.
 5. A display deviceprovided with a touch sensor according to claim 1, further comprising: aselection circuit electrically connecting the plurality of commonelectrodes to a driving circuit in the display operation period, andelectrically connecting the plurality of common electrodes to a touchdetection circuit in the touch detection operation period.
 6. A displaydevice provided with a touch sensor according to claim 5, the selectioncircuit further comprising: a plurality of selection switcheselectrically connecting the plurality of the signal lines to the drivingcircuit in the display operation period, and electrically disconnectingthe plurality of the signal lines from the driving circuit in the touchdetection operation period.
 7. A display device provided with a touchsensor, comprising: a plurality of gate lines arranged in a firstdirection to extend in a second direction crossing the first direction,a plurality of signal lines arranged in the second direction to extendin the first direction, a plurality of display elements provided inareas districted by the plurality of the gate lines and the plurality ofsignal lines, a plurality of common electrodes separated from eachother, arranged in a matrix, and overlapping the plurality of gate linesand the plurality of signal lines as seen in plan view, and a pluralityof pixel electrodes opposed to the plurality of common electrodes,wherein a display operation and a touch detection operation areperformed in a time divisional manner, wherein in a display operationperiod, the plurality of gate lines are supplied with selection signalsto select one or more display elements in a row direction among theplurality of display elements, and the plurality of pixel electrodes aresupplied with a plurality of display signals through the plurality ofsignal lines, wherein the plurality of common electrodes are selectivelysupplied with an alternating voltage signal and sense an external objectby a self-detection method, and at least the plurality of gate lines ofthe plurality of gate lines and the plurality of signal lines are in afloating state in a touch detection operation period.
 8. A displaydevice provided with a touch sensor according to claim 7, wherein theplurality of gate lines and the plurality of signal lines are notelectrically connected to a touch detection circuit.
 9. A display deviceprovided with a touch sensor according to claim 7, wherein the pluralityof gate lines and the plurality of signal lines are in a floating state.